Thermal performance of industrial-grade CH₃COONa·3H₂O-based composite phase change materials in a plate heat storage unit

Sodium acetate trihydrate (SAT) is considered as a promising material for medium- and low-temperature (<80 °C) thermal energy storage owing to its appropriate phase change temperature, large heat storage capacity, weak corrosion, and low cost. To adapt to the large-scale application, industrial-grade SAT-based composite phase change materials (PCMs) were prepared. Supercooling, phase separation, and thermophysical properties of composite PCMs were analyzed by experiments. Charging/discharging performances of such PCMs in a plate heat storage unit were investigated by simulation. The results showed that 4 wt% sodium pyrophosphate decahydrate (SPD) and 4 wt% polyacrylamide (PA) both of industrial grade could effectively solve the phase separation and supercooling of SAT. Composite PCMs was found to have a melting temperature of 54.2 °C and a latent heat of 211.8 J/g. To achieve a good charging/discharging performance, PCMs loading volume should be close to 100% for avoiding the space between the wall and PCMs. The temperature difference between the wall and PCMs was also required to exceed 8–10 °C both in charging and discharging process. Thickness of plate unit should be less than 80 mm. The results of this work could provide a foundation for the large-scale thermal energy storage applications of SAT.